The Vulcan XH558 maintenance team reports a positive update for September 2025, following recent challenges with the aircraft’s electrical system. The aircraft’s 200v distribution system, which powers the air brake motors, Powered Flying Control Units (PFCUs), and other 3-phase, 200v, 400Hz systems, had previously failed, preventing functional checks across the aircraft. Investigations revealed that surface corrosion on multiple fuses in the electrical bay and a short on fuse 40R, caused by a minor leak at the attachment point between the vertical stabiliser and the bay, were responsible for the failure. Additional distribution fuses on the sync bar had also blown. A full inspection confirmed that, aside from these issues, the electrical system was in remarkably good condition, including healthy busbars.
To prevent similar problems in the future, dehumidifiers have been installed in the electrical bay to reduce humidity levels. Minor follow-up work remains, including replacing a few aging resistors in the distribution panel indicator lights, which are currently showing dim or inconsistent illumination. With the 200v system restored, functional checks were completed on key aircraft systems, including flying control surfaces, bomb doors, air brakes, lights, and fuel pumps. During these checks, No.2 PFCU on the port aileron and the No.6 fuel pump were found to have blown fuses. Replacement of the affected fuses resolved both issues.
The maintenance team is now preparing to test and re-fit the Aircraft Auxiliary Power Pack to re-establish the electrical link to the main distribution system. Other work scheduled for the remainder of the season includes bleeding the bomb doors, replenishing hydraulic system pressure via the hydraulic power pack, cleaning fuel system relay contacts, performing routine lubrication and maintenance, refilling fire bottles, conducting an engine dry run and compressor wash, and repairing and testing the No.6 starboard fuel pump, which had experienced a wiring loom disconnection due to perished wiring.
Despite the extensive workload, the team remains committed to completing these tasks before the end of the season. The XH558 team also expressed gratitude for public engagement throughout the year, welcoming questions, suggestions, and stories related to the aircraft and its systems. To support the Vulcan to the Sky Trust, www.vulcantothesky.org
